Natural Ocean "Thermostat" might protect some coral reefs

Published: Friday, February 8, 2008, 13:36 [IST]

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Washington, Feb 8 : A new study has found evidence that a natural ocean "thermostat" appears to be regulating sea-surface temperatures in a biologically diverse region of the western Pacific, which might help in the protection of some coral reefs.

The study was carried out by scientists at the National Center for Atmospheric Research (NCAR) and Australian Institute of Marine Science (AIMS).or the research, the team, led by NCAR scientist Joan Kleypas, looked at the Western Pacific Warm Pool, a region northeast of Australia where naturally warm sea-surface temperatures have risen little in recent decades.

As a result of this, the reefs in that region appear to have suffered relatively few episodes of coral bleaching, a phenomenon that has damaged reefs in other areas where temperature increases have been more pronounced.

Caused due to global warming, coral bleaching involves corals turning white after expelling the colorful microscopic algae that provide them with nutrition. Unless cooler temperatures return in a few days or weeks, allowing algae to grow again, bleached corals often collapse and die.

The study lends support to a much-debated theory that a natural ocean thermostat prevents sea-surface temperatures from exceeding about 88 degrees Fahrenheit (31 degrees Celsius) in open oceans.

If so, this thermostat would protect reefs that have evolved in naturally warm waters that will not warm much further, as opposed to reefs that live in slightly cooler waters that face more significant warming.

"Global warming is damaging many corals, but it appears to be bypassing certain reefs that support some of the greatest diversity of life on the planet," said Kleypas.

"In essence, reefs that are already in hot water may be more protected from warming than reefs that are not. This is some rare hopeful news for these important ecosystems," he added.